XIII Abortion in the Demographic Transition Abdel R. Omran Regulation of the size and distribution of population has been practiced by human communities since time immemorial. The availability of food, the hostility of the environment, and the desire for life's conveniences continue to impinge upon man in his collective setting. In this age-old struggle between large numbers and limited resources, man has been aided by involuntary forces such as epidemics, famines, and wars; however, these scourges alone did not adequately mitigate population pressures. Voluntary methods practiced in an effort to temper the population problem have a long tradition. Since ancient times, voluntary fertility regulation has included infanticide, abortion, abstinence, and prolonged lactation, as well as attempts at conception control of both a magical and rational nature. From his careful review of the medical history of birth control, Himes (1) cites abortion as the chief means of fertility control in primitive societies. He reports that the earliest known written abortifacient recipe is a Chinese one more than 4,600 years old. Abortion was known in ancient Egypt, Greece, and Rome (1, 2). Several Greek philosophers, including Aristotle (3), sanctioned abortion to limit family size. Hippocrates, on the other hand, created reluctance among physicians to induce abortion and imbued certain instances of its practice with a sense of criminality (2, p. 459; 4). This reluctance remains with us even today, and the question of "criminality" is still disputed. Intriguing questions about the impact of abortion on fertility have been raised in recent years. During the past few centuries a successful transition from high, death rates and high birth rates to low death rates and low birth rates has occurred in western countries. This demographic transition (5) accompanied social, economic, and technological developments. Starting with a gradual decline in mortality, it was followed many decades later by a gradual decline in fertility. Abdel R. Omran is Associate Professor of Epidemiology, School of Public Health, University of North Carolina.rtensive Disease in Memphis, Tennessee, 1920-1960,"/ ChronicDis, 19, 1966. pp. 847-856.